Drug use and abuse is a major public health problem that can lead to serious health consequences, criminal involvement, employment problems, strained relationships, homelessness, poor treatment compliance and outcomes, and lower quality of life. Drug treatment can be effective in community-based settings, but drug users tend to under-utilize these treatment options and instead seek services in emergency rooms (ER) and other acute care settings. These settings tend to be the most expensive and least effective way of addressing drug problems. Research on substance use disorders consistently shows that drug problems typically require treatment over the course of several months. Recent research also shows that drug-related ER usage is increasing, resulting in billions of dollars in costs to the public health care system. The costs are even higher when other drug-treatment services and criminal justice expenditures are considered. Research on the burden of alcohol and associated ER and acute care service use is well developed, but little is known about drug- related burden and associations. Increasing this body of research is necessary given recent evidence which suggests that the consequences of drug use on ER and primary care service settings may be greater than alcohol alone. This research is needed to help ensure adequate policies and funding mechanisms to treat these chronic conditions in community-based settings. This research can also contribute to the development of effective and efficient assessments and brief interventions appropriate for ER and acute care settings. Finally, identifying repeat ER and acute care service users, and describing their clinical and psychosocial profiles, can lead to targeted approaches for treatment persons who have the greatest impact on the health care system. Following the recommendations of leading experts, this study will use a population- based survey to help address the foregoing gaps in knowledge. The specific aims of the study are to: 1) Examine patterns of drug use among persons who receive ER services and acute care services;2) estimate the attributable risk of ER care and acute care services associated with drug use;and 3) identify service utilization patterns and characteristics of drug-related repeat ER and acute care service users. PUBLIC HEALTH RELEVANCE: The purpose of this study is to determine the risk of emergency room use associated with major drugs of abuse. This study will also examine patterns of treatment following drug-related emergency room care. The results will help reveal the burden of drug use on the public system of care and suggest ways to more effectively structure treatment and policy.